All-

The help I've received on this forum is beyond compare. You guys really make it possible for someone to figure this stuff out. Thanks so much.

We are in the planning stages of a relatively small, but plumbing heavy addition to our home. The space is 10' L x52"W and will span three floors. I've decided to do as much of the work myself as is possible, reasonable and legal, including drawing up the plans for the permit. I am in this process and would like some guidance as I make some of decisions. Would really appreciate any help possible. For what it is worth, I live in Washington, DC where we are subject to the following codes/regulations:

2000 International Building Code
2000 International Plumbing Code
2000 International Residential Code

So, my initial questions, somewhat varied in scope are:

1) We are planning to install a powder room in one part of the addition. Because of how the addition ties into the home the dimensions are approximately 38"L x 52" W. Is this even possible, pursuant to code? Are there really low profile toilets? We plan on using a pocket door, so it will eliminate that intrusion and we've found a 16"x16" vanity, which should help. Any advice on layout? What are suggested clearances for a)comfort and b) code?

2) I am trying to figure out the best way to tie the new addition into the house's plumbing. The addition will contain a powder room (toilet and lav) and a full bath(tub/shower, lav and toilet). My thinking is to run a 3" stack up the side of the addition that would service both the powder room and the full bath, venting out the roof. There seems to be two options to tie this 3" stack into the house's plumbing.

Option 1 - Run it in a soffit along my basement ceiling, tying into the house's main cast iron stack. The stack is at least 3", but could be 4" (as an aside, how can I figure that out?). That would involve a straight run of about 13' where it would have to 90 and then run another 4' or so to the stack. Currently this main stack services just one bathroom (tub/shower, lav and toilet).

Option 2- We could run the 3" addition stack straight into the ground, run it through the house's foundation, and tie it into a 3" cast iron drain line under the slab of my finished basement. This drain line services a full bath (tub/shower, lav and toilet, as well as a washing machine and bar sink).

What are your opinions on these two options? Obviously Option 2 would be cleaner (no soffit), but much more disruptive. I figure overall the soffit would have be about 6 or 7" to accommodate the slope of the pipe 1/4" per foot, right?) Any other suggestions?

I am sure there are many more questions to come, but for now, this would really help get me oriented.

Thanks so much!

Powder Room: you have very limited space. Here is what you could do: Use wall mount toilet (geberit frame / stark bowl). This set up protrudes only about 16" away from the wall ( tank built in the wall ). I had installed one of those in 4'x4' room and it came out just fine. Porcher make skinny wall hung sink that is perfect for your situation. It protrudes only 8.2" away from the wall. See photo...

The wall mount toilet requires 2x6 framing, right? Can it be hung on an exterior wall?

Correct, it requires 2x6" framing. You could fur it up just on the back wall to accommodate the frame installation. Yes, it can be installed on exterior wall. Are you concerned about freezing?

That would be my only concern, but the space would be heated and the wall insulated. Should I not be worried?

They're pricey though, no?

Frame runs about $400.00, the bowl about $300.00, trim about $200.00. This is what they look like...

You could put in regular toilet - but you may be running out of space. Regular toilet protrudes about 31" away from the wall. Do test: put chair with front edge 21" away from the wall, sit on it, imitate position just like sitting on toilet and try to get up. Don't forget, there is a sink on your right, too... Let me know how you did...

Is this more of a comfort issue or a code issue?

Code mandates certain dimensions that translate to comfort.

Stubits, where do you live, how thick is your insulation and what is your exterior wall material?

The walls will be framed 2x6, clad in hardie plank(cement fiberboard). Planning on putting in R-19 fiberglass batt insulation. We live in Washington, DC, so we definitely get some cold days. The room will be heated.

We have another toilet on an exterior wall, an 8" thick brick wall with no insulation. We haven't had problems.

You should be OK, you rarely get snow so it's not like Chicago. We are getting 6" more of the white stuff tonight with over nights lows of 15. Any way to get insulation into that brick cavity or is it solid brick/masonary?

That's one of the projects on the "to do" list, actually.

The exterior is solid brick, but there is a stud wall in front, albeit a very poorly constructed stud wall. The PO did a real hack job on it, there are top and bottom plates, but few studs, some of which run diagonally. They actually walled right over a window without sealing the window up, so I will fix that eventually to, but not sure quite yet how. I am thinking of mounting a wall fountain where the window is. It would be too hard to match the brick, really. I think my only option on the insulation is to blow it in through a hole in the wall. Any other suggestions?

That said, the wall where I might mount the wall toilet would be insulated.

Other than a wall mount toilet, any suggestions for such a small powder room? Also, any thoughts on my other question?

Bump...

So, a bit of a math question. Is it possible and code friendly to run 3" PVC through 2x12 joists for a distance of 13' while keeping the 1/4" per 1' slope? I have done the math and I think the answer is yes, but would appreciate any insight.

The hole may be no more than 1/3 the actual measured depth of the joist. Figuring that your 2x12 has actual depth of 11 1/2" , you can drill up to about 3 3/4" inch hole. The hole must have it's edge at least 2" from the bottom or top of the joist. Those holes are also not permitted to be any closer than 2" to any other hole or notch.

Math: you will have about 3 3/4" of slope to play with. You have 13' of pipe to run. Slope for 3" pipe is 1/4" per foot. Actual O.D of pipe is 3 3/8" . Therefore, you will use 3 1/4" for slope. Conclusion: yes, you should be fine , at least mathematically speaking, but you will be hitting maximums. Measure carefully. Don't forget that 90 ell on each end may set you lower or higher.

Now, It is bad idea to drill across 13' of joists across middle of the room. That certainly will create week spot. Plan carefully. Use common sense. Also, DRILL, do not chop it up with sawzall. You can buy Milwaukee drill bit made exactly for 3" PVC / ABS pipe or Lenox HoleSaw bits of the same size. Wear goggles and good pair of gloves.

Milo-

Thanks!

Any other tips on how to minimize damage to the joists?

And is it OK to feed 2.5 baths into a 3" stack?